where does code resides

Or try not to use any of the C library at all!

printf() pulls is a lot of code.

You may have code to initialise/destroy stdin/stdout/stderr being exected before/after main() is called - this also pulls in malloc() etc.

Calling your code alt_main() will remove the stdio stuff (this probably isn't the official way to do it! but worked for me).

The linker map file (possibly with cross references) will show why each library function was added. Although I don't know how to persuade the IDE to generate it.